factor % ./Hello\ world/hello-ui 
The die word was called by the library. Unless you called it yourself,
you have triggered a bug in Factor. Please report.
Starting low level debugger...
  Basic commands:
q                -- continue executing Factor - NOT SAFE
im               -- save image to fep.image
x                -- exit Factor
  Advanced commands:
d <addr> <count> -- dump memory
u <addr>         -- dump object at tagged <addr>
. <addr>         -- print object at tagged <addr>
t                -- toggle output trimming
s r              -- dump data, retain stacks
.s .r .c         -- print data, retain, call stacks
e                -- dump environment
g                -- dump generations
data             -- data heap dump
words            -- words dump
tuples           -- tuples dump
refs <addr>      -- find data heap references to object
push <addr>      -- push object on data stack - NOT SAFE
code             -- code heap dump
READY
.c
==== CALL STACK:
frame: 7f65fe59efc8
executing: f
scan: f
word/quot addr: 1
word/quot xt: 7f65ed560630
return address: 7f65ed56065e
frame: 7f65fe59efa8
executing: [ #<not a string: f> T{ #<not a string: f> 0 0 { T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } } } #<not a string: f> #<not a string: f> #<not a string: f> T{ #<not a string: f> 0 0 { T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } T{ #<not a string: f> f } } } #<not a string: f> #<not a string: f> #<not a string: f> T{ #<not a string: f> { } 0 }... ]
scan: 72
word/quot addr: 7f65f1c290d4
word/quot xt: 7f65ed63fd90
return address: 7f65ed63ffd1
frame: 7f65fe59ef88
executing: f
scan: f
word/quot addr: 1
word/quot xt: 7f65ed627bf0
return address: 7f65ed627f6b
frame: 7f65fe59ef68
executing: f
scan: f
word/quot addr: 1
word/quot xt: 7f65ed54f490
return address: 7f65ed54f50e
frame: 7f65fe59ef48
executing: f
scan: f
word/quot addr: 1
word/quot xt: 7f65ed560120
return address: 7f65ed56015b
READY
.s
==== DATA STACK:
T{ #<not a string: f> [ #<not a string: f> ] T{ #<not a string: f> T{ #<not a string: f> [ f ] T{ #<not a string: f> T{ #<not a string: f> #<not a string: f> f "Hi" f f { #<not a string: f> #<not a string: f> } { #<not a string: f> #<not a string: f> #<not a string: f> #<not a string: f> #<not a string: f> } f } [ #<not a string: f> ] } } T{ #<not a string: f> [ "Hello world" #<not a string: f> #<not a string: f> ] [ #<not a string: f> ] } } }
"No method"
"No method"
READY
.r
==== RETAIN STACK:
READY